PROBLEM 11.64 (Continued)
Problem 11.65
A particle moves in a straight line with the velocity shown in the
figure. Knowing that x = –
48 ft at t = 0, draw the a–t and x–t
curves for 0 < t < 40 s and determine (a) the maximum value of
the position coordinate of the particle, (b) the values of t for
which the particle is at a distance of 108 ft from the origin.
PROBLEM 11.65 (Continued)
PROBLEM 11.66
A parachutist is in free fall at a rate of 200 km/h when he opens his parachute at
an altitude of 600 m. Following a rapid and constant deceleration, he then
descends at a constant rate of 50 km/h from 586 m to 30 m, where he maneuvers
the parachute into the wind to further slow his descent. Knowing that the
parachutist lands with a negligible downward velocity, determine (a) the time
required for the parachutist to land after opening his parachute, (b) the initial
deceleration.
PROBLEM 11.66 (Continued)
PROBLEM 11.67
A commuter train traveling at 40
mi/h is 3 mi from a station. The
train then decelerates so that its
speed is 20 mi/h when it is 0.5 mi
from the station. Knowing that the
train arrives at the station 7.5 min
after beginning to decelerate and
assuming constant decelerations,
determine (a) the time required for
the train to travel the first 2.5 mi,
(b) the speed of the train as it
arrives at the station, (c) the final
constant deceleration of the train.
PROBLEM 11.68
A temperature sensor is attached to slider AB which moves
back and forth through 60 in. The maximum velocities of the
slider are 12 in./s to the right and 30 in./s to the left. When the
slider is moving to the right, it accelerates and decelerates at a
constant rate of 6 in./s
2
; when moving to the left, the slider
accelerates and decelerates at a constant rate of 20 in./s
2
.
Determine the time required for the slider to complete a full
cycle, and construct the v – t and
xt
curves of its motion.
PROBLEM 11.69
In a water-tank test involving the launching of a small model
boat, the model’s initial horizontal velocity is 6 m/s, and its
horizontal acceleration varies linearly from
2
12 m/s
at 0t
to
2
2 m/s
at t
1
t
and then remains equal to
2
2 m/s
until
1.4 s.t Knowing that 1.8 m/sv when
1
,tt
determine
(a) the value of
1
,t
(b) the velocity and the position of the
model at 1.4 s.t
PROBLEM 11.69 (Continued)
PROBLEM 11.70
The acceleration record shown was obtained for a small
airplane traveling along a straight course. Knowing that
x
0
and 60 m/sv when
0,t
determine (a) the velocity and
position of the plane at
20 s,t
(b) its average velocity
during the interval 6 s 14 s.t